The Bing map link on trip advisor is wrong - Google maps are better but still not clear..
The Riad is about 10 minutes walk inside the Medina walls from the NW gates, and about 20 minutes walk to the main Djeema el Fna square in the middle of the Medina. Finding the square from the Riad is OKish but finding your way back is difficult - lots of forks and dead ends and not many land marks visible from the covered souks. Take a compass or GPS and a good map (although there aren't many street name signs and those there are, are likely to be called something else on the map). Taxis can only get to about 100m from the Riad - the biggest landmark is the Sid Ben Slimane mosque but the Riad is about 30m SW of the mosque on the far side from Rue Sidi Ben Slimane where the main entrance is.
Taxi from the airport should take about 20 minutes and we paid 200Drms - which we were assured was the standard tarrif - but we only paid 80 to get from the Riad to the airport 3 days later.
If the Taxi drops you outside the Ecole Primaire Ahmed Ennou, then facing the wall of the schoolgo to your right, take the first left and follow the zig-zag alleyway to your first right again an the Riad is the first door on the right - there is a bell high-up on the right of the door. You will think you are disappearing down a rabbit warren to find it but the Riad courtyard is a gem.